[Ada] Fix glitch in debug info for renaming

[Eric Botcazou]

GDB cannot inspect renamings declared at library level when it relies on the 
special __XR variable generated as per the GNAT encodings.

Tested on x86_64-suse-linux, applied on the mainline.


2016-12-07  Pierre-Marie de Rodat  <dero...@adacore.com>

        * gcc-interface/decl.c (gnat_to_gnu_entity): When they are global,
        consider ___XR GNAT encodings variables for renamings as static so
        they have a location in the debug info.

-- 
Eric Botcazou
Index: gcc-interface/decl.c
===================================================================
--- gcc-interface/decl.c	(revision 243340)
+++ gcc-interface/decl.c	(working copy)
@@ -672,6 +672,7 @@ gnat_to_gnu_entity (Entity_Id gnat_entit
 				   VAR_DECL, gnu_entity_name, gnu_type);
 	    SET_DECL_VALUE_EXPR (gnu_decl, value);
 	    DECL_HAS_VALUE_EXPR_P (gnu_decl) = 1;
+	    TREE_STATIC (gnu_decl) = global_bindings_p ();
 	    gnat_pushdecl (gnu_decl, gnat_entity);
 	    break;
 	  }